1. Field of the Invention
The present invention relates generally to mail sorting systems and, more particularly, to a method and system for converting mail between trays in a multiple pass mail sorting system.
2. Discussion of the Related Art
Currently, a variety of automated systems are used to sort flats mail. These automated mail sorting systems reduce cost and increase efficiency. The cost is reduced in automated mail systems by the use of less floor space and less manpower. The efficiency is increased because the time and space required to sort the mail in an automated system is much less than when sorting is performed manually. Some automated mail sorting systems require more than one pass and more than one type of tray in order to sort the mail into a desired sequence, such as carrier route. One of the biggest issues with multiple pass sorting systems is transferring mail back to the input of the sorting system after the first pass (or any pass other than the final pass). Another issue can be the need for multiple, separate systems for feeding the mail back into the sorter or sending mail to dispatch. This can lead to the use of more floor space and all but one of the systems will always not be in use (e.g., when mail is being sent to dispatch the system for sending mail to the sorting system will not be used and visa-versa).
One solution to transferring mail between passes is to use a system that would unload the mail from one tray and place it directly into another. This system does a one-to-one transfer (e.g., mail from the first tray goes directly into the second tray). A one-to-one transfer hurts efficiency, especially in systems where the various types of trays used have different maximum capacities. The efficiency is hurt firstly by the fact that if a tray is only partially filled then the transfer system will still transfer the mail to the next tray without trying to create a larger stack to fill the next tray (e.g., if the first tray has one inch of mail then the second tray will receive one inch of mail). Secondly, the system is limited by the maximum capacity of the smallest tray (e.g., if the tray used for dispatch has a maximum capacity of 15 inches and the tray used for sorting has a maximum capacity of 9 inches, then in a system with one-to-one transfer the dispatch trays will always have at least 6 inches of empty space).
Therefore, a need exists for an improved method and system for transferring mail between trays in a multiple pass mail sorting system.